Understanding the folding, assembly, and transport of viral glycoproteins is of general interest, and practical importance, since it could lead to greater understanding of the antigenic structure of viral glycoproteins; information critical for designing vaccines that induce antibodies that neutralize viral infectivity and confer protection against infection. We have studied the biosynthesis of influenza virus glycoproteins using monoclonal antibodies (MAbs) that discriminate between various forms of the glycoproteins present within virus infected cells. To summarize the major findings: Folding of the hemagglutinin (HA) glycoproteins occurs rapidly during biosynthesis, possibly even co-translationally. HA oligomerization begins 1 to 2 minutes following synthesis. In the presence of an agent which inhibits glycoprotein transport form the endoplasmic reticulum (e.r.), oligomerization occurs detectably within the e.r., under normal circumstances however, oligomers are only detected in post-endoplasmic reticulum compartments. A new panel of MAbs was produced, and experiments initiated, to examine similar events in the biosynthesis and assembly of the other influenza virus glycoprotein the neuraminidase.